/Engine/Source/Runtime/Engine/Public/Physics/ImmediatePhysics/ImmediatePhysicsChaos/ImmediatePhysicsSimulation_Chaos.h
Sets the number of active bodies. This number is reset any time a new simulated body is created
void SetNumActiveBodies ( int32 NumActiveBodies, [TArray](API\Runtime\Core\Containers\TArray)< int32 > ActiveBodyIndices )